A connecting fitting for a mixing valve is described in Austrian Patent No. 177 382. A comparatively simple and flat coupler is provided to which the mixing valve is attached with a flanged coupling joint. With this device it is required that the coupler be positioned precisely in the structure wall, since a subsequent adjustment is not possible with the mixing valve mounted.
Furthermore, during installation the pipe system connections for cold and warm water in the concealed coupler can be exchanged or inadvertently switched. This is first noticed chiefly when the mixing valve is connected. To make the correct connections a new installation of pipes is required which is extremely expensive, especially with concealed pipes.
Further, a sanitary valve connecting member is described in European Patent No. 0 119 960, in which a mixing valve with a plug member is insertable in a cavity or hole in a coupler. The coupler should comprise a housing, in which a receiving member is mounted which contains the receiving cavity for the plug member. In this device, indeed, a subsequent correction of exchanged connections and an adjustment of the mixing valve is possible. It is, however, relatively complicated and thus expensive and involves considerable expense in construction. Moreover, a comparatively deep coupler is needed by the required receiving cavity for the plug member.